EP0369898A1 - Process and apparatus for the manufacture of a shoulder strap for clothing, especially a shoulder strap for brassieres - Google Patents

Abstract

The machine according to the invention comprises a first subassembly permitting the assembly of a main ribbon on two buckles and a second subassembly for the assembly of an auxiliary ribbon. The first subassembly comprises buckle supports (55, 56), a longitudinal drawing lip (12), a welding assembly (51), and threading fingers (13, 14, 18, 25, 28). The upper assembly carrying the upper threading fingers (13, 14, 25) and the welding assembly (51) is movable in longitudinal translation on guides (58) of the frame (50), in order to bring the welding assembly (51) opposite either a cutting anvil (24) or a welding anvil (19). <IMAGE>

Description

The present invention relates to a method and a machine for assembling loops and ribbons to form an adjustable garment strap such as a bra strap.

Bra straps generally include a main ribbon, a first loop with two slits, a second loop and an auxiliary ribbon. The main ribbon passes for the first time in the loop with two slits by crossing one and the other of the two slits and passing around the central crosspiece separating them, then passes in the second loop and returns in the first loop with two slots to pass again, in the same direction, around the central crosspiece. The auxiliary tape goes through the second loop. The two ends of auxiliary tape are welded to each other. The main ribbon end forms a loop welded on itself around the central crosspiece of the first loop with two slots. This produces a strap of adjustable length. The difficulty comes from the fact that it is necessary to pass the ribbon several times through the loop slots to make said strap, the ribbon passages being long and tedious operations.

We have already looked for means allowing the automatic threading of the ribbons in the loops to form the bra strap. For example, patent FR-A-2 515 009 describes a method and a device for this automatic threading of ribbons in the loops. Tests have shown that the process and the device described in this document lead to operating faults which make them ineffective for industrial production. For example, the ribbon is not held while the threading fingers are threaded to pass the ribbon through the loop slots. As a result, the threading fingers produce a symmetrical sliding of the ribbon in the slots on either side of the threading finger, so that the threading finger is generally not capable of sliding the end. free of tape until passing it to the other side of the slot. The later stages of the process lead to a blockage of the ribbon in the slots, so that the fingers can no longer pass through the slots and break when actuated.

This known method and device also lead to welding defects of the ribbon on itself, either because the welding is carried out by insufficient means, or because the ribbon is not correctly positioned and maintained during this welding.

Also, the structure of the machine described in this document, as well as the operating method associated with it, do not allow bra straps to be produced whose length is adjustable within a sufficient range. For example, the size of certain mechanical elements prevents the making of very short bra straps.

The method and the device described in this document do not allow the assembly of a complete bra strap: the auxiliary tape must be adapted by subsequent operations, the method only targeting the assembly of the main tape on the two curls.

Document CE-A-1 547 578 also describes a method and a device for the automatic threading of ribbons in the loops. In this document, the loops are maintained in vertical planes, the ribbon being threaded horizontally. In a first station, the ribbon is threaded by a kind of needle into a first slot of a loop with two slots, then folded and passed into the second slot by a threading finger, and then sewn on itself. In a second station, the free end of the ribbon is threaded by a second needle onto a second loop, the assembly formed by the second needle, the free end of the ribbon and the second loop being then turned over and brought by translation into the second slot of the first loop, the free end of the ribbon then being deflected and then threaded into the first slot of the first loop by a threading finger.

This method and this device require complex movements of mechanical parts, and in particular a movement of both rotation and translation of the second needle to thread the free end of the ribbon into the second loop and turn the assembly over so bring the free end of the ribbon into the first loop. The complexity of such a movement significantly increases the cost of such a device, decreases its reliability and speed. No solution is given to correctly position the loops relative to each other at the end of assembly, and to avoid subsequent manual rework.

Document US-A-3,587,947 also describes a method and device for threading the ribbons into the loops, according to which the loops are held horizontally in two positions offset vertically and horizontally, and the ribbons are threaded by fingers. threading passing simultaneously through the two loops. No means is provided for securing the ribbon to the central crosspiece of the first loop, and the general structure of the device would not allow it.

The object of the present invention is in particular to avoid the drawbacks of known methods and devices, by proposing a new method and a new device for assembling bra straps allowing safe and reliable operation to be usable for mass production. bra straps.

Another object of the invention is to allow the production of bra straps, the length of which can be much shorter than in known methods. By way of example, in known methods, it is considered that the minimum length between the free end of the main strip and the second loop is approximately 270 millimeters; on the other hand, with the method and the device of the invention, it is possible to produce suspenders whose length between the free end of the main ribbon and the second loop is of the order of 160 millimeters.

Another object of the invention is to allow automatic programming of the lengths of straps, without any disassembly of tools.

Another object of the invention is to correctly position the second loop while lengthening the bra strap, so as to avoid subsequent manual rework. It has in fact been found that, in known devices, the second loop is not positioned at the end of the first strip, but in the vicinity of the first loop, which requires them to be separated from one another later. This drawback is eliminated in the present invention.

Another object of the invention is to carry out the total mounting of the bra strap, by adapting the additional ribbon in the second loop.

• a/ on introduit une première boucle à deux fentes dans un support fixe horizontal de première boucle en disposant les fentes transversalement par rapport au sens de dévidement longitudinal du ruban, et on introduit une seconde boucle dans un support horizontal de seconde boucle approprié disposé en amont du support de première boucle à deux fentes,
• b/ on attrappe, au moyen d'une pince mobile, la première extrémité du ruban de réserve, et on déplace longitudinalement ladite pince mobile d'une distance fixe déterminée pour faire passer le ruban au dessus de la première boucle à deux fentes et amener son extrémité au delà de ladite première boucle à deux fentes selon une longueur prédéfinie,
• c/ on amène un doigt de maintien en appui de haut en bas sur le ruban pour le pincer contre la première fente de première boucle à deux fentes,
• d/ on desserre la pince et on enfonce un premier doigt d'enfilage de haut en bas dans la seconde fente de première boucle à deux fentes pour introduire la première extrémité de ruban dans ladite seconde fente,
• e/ on rabat cette première extrémité de ruban sous la première boucle à deux fentes, on introduit l'extrémité rabattue dans la première fente en enfonçant un second doigt d'enfilage de bas en haut dans ladite première fente,
• f/ on soude la première extrémité de ruban sortant de la première fente sur la portion de ruban d'entrée entre une enclume de soudure et une sonde ultrasonore disposées au voisinage et en amont de la première boucle à deux fentes,
• g/ on tire une longueur réglable de ruban au moyen d'un doigt mobile autour duquel passe une portion intermédiaire de ruban, la première extrémité de ruban étant retenue par la première boucle à deux fentes, le ruban de réserve étant freiné par un dispositif de freinage,
• h/ on coupe le ruban, au moyen de la même sonde ultrasonore que l'on a déplacée longitudinalement vers l'amont de la distance voulue, et on introduit par un doigt d'enfilage de seconde boucle la seconde extrémité de ruban, selon une longueur prédéfinie, dans la seconde boucle maintenue horizontalement dans le support de seconde boucle,
• i/ on effectue, entre la première boucle à deux fentes et l'ensemble formé par le ruban et la seconde boucle, un mouvement relatif de rotation d'axe transversal autour de la traverse centrale de première boucle à deux fentes, pour dégager la première fente de première boucle à deux fentes, et on amène la seconde extrémité de ruban contre la face de première boucle à deux fentes par laquelle sort le ruban, au voisinage de la première fente,
• j/ on amène un doigt de maintien en appui sur le ruban pour le plaquer contre la seconde fente de première boucle à deux fentes, et on enfonce un troisième doigt d'enfilage dans la première fente pour introduire la deuxième extrémité de ruban dans ladite première fente, on rabat ladite seconde extrémité de ruban de l'autre côté de ladite première boucle en direction de la seconde fente, on introduit l'extrémité rabattue dans la seconde fente en enfonçant un quatrième doigt d'enfilage dans ladite seconde fente,
• k/ on éjecte l'ensemble ainsi réalisé.

To achieve these and other objects, the method according to the invention comprises the succession of the following steps:

• a / a first loop with two slots is introduced into a horizontal fixed support of the first loop by placing the slots transversely with respect to the direction of longitudinal unwinding of the ribbon, and a second loop is introduced into a horizontal support of the appropriate second loop placed upstream the first loop support with two slots,
• b / we catch, by means of a movable clamp, the first end of the reserve ribbon, and said movable clamp is moved longitudinally by a fixed fixed distance to pass the ribbon over the first loop with two slots and bring its end beyond said first loop with two slots according to a predefined length,
• c / a holding finger is brought up and down on the strip to pinch it against the first slot of the first loop with two slots,
• d / the clamp is loosened and a first threading finger is inserted from top to bottom into the second slot of the first loop with two slots to introduce the first end of the ribbon into said second slot,
• e / this first end of the ribbon is folded under the first loop with two slots, the folded end is introduced into the first slot by inserting a second threading finger from bottom to top in said first slot,
• f / the first end of the tape leaving the first slot is welded to the portion of input tape between a welding anvil and an ultrasonic probe arranged in the vicinity and upstream of the first loop with two slots,
• g / an adjustable length of ribbon is pulled by means of a movable finger around which passes an intermediate portion of ribbon, the first end of ribbon being retained by the first loop with two slots, the reserve ribbon being braked by a device braking,
• h / the ribbon is cut, by means of the same ultrasonic probe which has been moved longitudinally upstream by the desired distance, and the second end of the ribbon is introduced by a second loop threading finger, according to a predefined length, in the second loop maintained horizontally in the second loop support,
• i / between the first loop with two slots and the assembly formed by the ribbon and the second loop, a relative movement of rotation of a transverse axis is carried out around the central crosspiece of the first loop with two slots, to release the first first loop slot with two slits, and the second end of the ribbon is brought against the face of the first loop with two slits through which the ribbon exits, in the vicinity of the first slit,
• j / a holding finger is brought to bear on the ribbon in order to press it against the second slot of the first loop with two slots, and a third threading finger is pressed into the first slot to introduce the second end of the ribbon into said first slot, the second end of the ribbon is folded down on the other side of the said first loop in the direction of the second slot, the folded end is introduced into the second slot by inserting a fourth threading finger into the said second slot,
• k / the assembly thus produced is ejected.

According to an advantageous embodiment:
- during step g /, the transverse finger is moved longitudinally over the first loop with two slots between a first upstream position and a second downstream position,
- Step i / is carried out by longitudinal displacement of the second loop over the first loop with two slots to a position located downstream of the first loop with two slots.

A device for implementing this method comprises, according to one embodiment, a frame, a reserve of tape, a reserve of first loops with two slots, a reserve of second loops, a first horizontal support for maintaining a first loop with two slots, a first horizontal support for holding a second loop, means for bringing loops from the reserves of loops in the loop supports, a movable clamp actuated by a drive means for catching the end of the ribbon at the outlet of the ribbon reserve and bring it along a longitudinal path beyond the first support of the first loop with two slots, two upper fingers for threading the ribbon and two lower fingers for threading the ribbon, vertically displaced, arranged opposite the two slots of the first loop with two slots on either side of said loop, means for driving the threading fingers in movements of t vertical ranslation generally perpendicular to the first loop, folding fingers to fold the end of the ribbon under the first loop with two slots between the second and the first slot, means for welding the ribbon around the central branch of the first loop to two slits and means for cutting the ribbon. According to the invention:
the first support of the first loop with two slots is fixed in longitudinal position on the frame,
the means for welding the ribbon comprise a mobile ultrasonic probe in longitudinal displacement parallel to the direction of movement of the ribbon between a welding position in which the ultrasonic probe is disposed in the vicinity of the first support of the first loop with two slots facing a welding anvil and a cutting position in which the ultrasonic probe is arranged in the vicinity and upstream of the first support of the second loop opposite a cutting anvil, the same ultrasonic probe successively performing the functions of the welding member and cutting member,
a transverse horizontal finger with longitudinal movement is driven by longitudinal drive means between a first position in which the finger occupies an intermediate zone between the two first loop supports and a second position in which the finger is downstream from the first support first loop with two slots, the second position of the transverse finger being adjustable by longitudinal displacement as a function of the length of the strap to be produced.

• - la figure 1 représente une vue de côté d'une bretelle de soutien-­gorge;
• - la figure 2 représente une vue de dessus de la même bretelle de soutien-gorge ;
• - les figures 3 à 14 illustrent le procédé d'assemblage du premier ruban sur la première et la seconde boucles ;
• - les figures 15 à 17 illustrent la mise à longueur du premier ruban de bretelle ;
• - les figures 18 à 22 illustrent l'assemblage du ruban auxiliaire sur l'ensemble formé par le ruban principal et les deux boucles ;
• - la figure 23 est une vue de face du premier sous-ensemble de dispositif selon la présente invention, pour l'assemblage du ruban principal et des deux boucles ;
• - la figure 24 est une vue schématique de côté du dispositif de la figure 23, montrant les moyens d'entraînement en translation verticale des doigts d'enfilage ;
• - la figure 25 est une vue schématique d'arrière montrant les moyens d'entraînement en translation verticale des doigts d'enfilage ;
• - la figure 26 illustre schématiquement la structure générale du dispositif de l'invention, avec une première partie pour l'assemblage du ruban principal sur les deux boucles, et une seconde partie pour l'adaptation du ruban auxiliaire ;
• - la figure 27 est une vue de face du second sous-ensemble de dispositif, permettant l'adaptation du ruban auxiliaire ;
• - la figure 28 illustre schématiquement les profils de sonde ultrasonore et d'enclumes du premier sous-ensemble ;
• - les figures 29 à 31 illustrent un détail de réalisation des moyens de coupe et d'étirement de ruban ;
• - la figure 32 illustre schématiquement un dispositif de traction du ruban pour le tendre avant soudure.

Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, among which:

• - Figure 1 shows a side view of a bra strap;
• - Figure 2 shows a top view of the same bra strap;
• - Figures 3 to 14 illustrate the method of assembling the first ribbon on the first and second loops;
• - Figures 15 to 17 illustrate the cutting to length of the first strap strap;
• - Figures 18 to 22 illustrate the assembly of the auxiliary ribbon on the assembly formed by the main ribbon and the two loops;
• - Figure 23 is a front view of the first device sub-assembly according to the present invention, for assembling the main ribbon and the two loops;
• - Figure 24 is a schematic side view of the device of Figure 23, showing the drive means in vertical translation of the threading fingers;
• - Figure 25 is a schematic rear view showing the drive means in vertical translation of the threading fingers;
• - Figure 26 schematically illustrates the general structure of the device of the invention, with a first part for assembling the main ribbon on the two loops, and a second part for adapting the auxiliary ribbon;
• - Figure 27 is a front view of the second device sub-assembly, allowing the adaptation of the auxiliary tape;
• - Figure 28 schematically illustrates the profiles of ultrasonic probe and anvils of the first sub-assembly;
• - Figures 29 to 31 illustrate a detail of embodiment of the ribbon cutting and stretching means;
• - Figure 32 schematically illustrates a device for pulling the ribbon to stretch it before welding.

Figures 1 and 2 show a bra strap that can be assembled by a device and according to a method of the present invention. This strap comprises a main ribbon 1 passing through a first loop with two slots 2 and through a second loop 3, and an auxiliary ribbon 4 passing through the second loop 3. As shown in the figures, the main ribbon 1 passes through a first slot 5 of the first loop with two slots 2, bypasses the intermediate crosspiece 6 and passes into the second slot 7 of the first loop with two slots, crosses a slot of the second loop 3, and returns to pass around the crosspiece 6 of the first loop with two slots 2 in the same direction as its first passage, between said intermediate crosspiece 6 and the first part of main ribbon 1. The first end 8 of main ribbon 1 is welded against the part of main ribbon 1 coming from the second loop 3. The auxiliary tape 4 passes through a slot in the second loop 3, and its first end 9 is welded against the opposite part of auxiliary tape 4.

It is understood that the operation of threading the ribbons in the loops is relatively long and tedious, and that this operation is also delicate because it strongly depends on the sliding conditions between the ribbons and the loops. We are therefore led to look for means allowing the threading of the ribbons in the loops, means which allow this threading for various ribbon structures, smooth or rough, wide or narrow.

Figures 3 to 14 illustrate the method for assembling the main ribbon 1 on the first loop with two slots 2 and on the second loop 3, from a reserve 10 of ribbon with longitudinal unwinding, from a reserve of first loops with two slots and a reserve of second loops.

In Figure 3, a first loop with two slots 2 is introduced on a fixed support, not shown, maintaining the first loop with two slots in a horizontal position, the slots being arranged transversely to the longitudinal unwinding direction 11 of the ribbon. A second loop 3 is introduced into a suitable horizontal second loop support, not shown, arranged upstream of the first loop support with two slots. The first end 8 of the reserve ribbon is caught, by means of a movable clamp 12, and said movable clamp 12 is moved longitudinally by a fixed distance L determined to pass the main ribbon 1 over the first loop with two slots 2 and bring its end beyond said first loop with two slots 2 according to a predefined length D.

In FIG. 4, a retaining finger 13 is moved up and down to bring it into contact with the ribbon 1, the retaining finger pinching the ribbon 1 against the first slot 17 of the first loop with two slots 2. The retaining finger 13 thus avoids the longitudinal sliding of the ribbon 1 on the first loop with two slots 2. Simultaneously, to improve this maintenance, a first flank clamp 22 can be brought to bear on the ribbon 1 to pinch it against the second loop 3. The sidewall clamp 22 can be maintained until the welding step which will be described later in relation to FIG. 7. The clamp 12 is loosened to release the first end 8 of the ribbon 1, and a first finger is pressed threading 14 from top to bottom in the second slot 15 of the first loop with two slots 2 to introduce said first end 8 of tape into said second slot 15. At the end of this operation, the end 8 of tape 1 hangs below the first b double slit 2.

In FIG. 5, a folding means 16 folds the first end 8 of ribbon under the first loop with two slots 2 in upstream direction, so that the protruding part of the tape 1 is arranged across the first slot 17 of the first loop with two slots 2.

In FIG. 6, a second threading finger 18 is inserted into the first slot 17 of the second loop with two slots 2, from bottom to top, to introduce the folded end of ribbon into said first slot 17. During this operation, the tape 1 is held under a slight tension by the reserve 10 of tape, which allows a sufficient elongation of the tape 1 to allow the total introduction of the protruding portion of tape into the first slot 17 as shown in the figure.

In FIG. 7, the second threading finger 18 is removed, and the ribbon 1 is again under slight tension by the effect of the reserve 10 of ribbon. According to an advantageous embodiment, the ribbon 1 is pulled upstream to slide it around the central crosspiece 6 of the first loop with two slots 2 and bring its first end 8 in the immediate vicinity of the first loop with two slots 2 The interest is twofold: the end 8 of the ribbon is better centered transversely relative to the loop 2; the welding of the tape 1 is carried out as close as possible to the loop 2. The end 8 of the tape rests on a welding anvil 19, arranged upstream and close to the support of the first loop with two slots 2. The first is welded end 8 of tape 1 leaving the first slot 17 on the portion of input tape 1 by pressing between said welding anvil 19 and an ultrasonic probe 20, by moving the ultrasonic probe 20 up and down to bring it into press against the tape and press it onto the welding anvil 19. The ultrasonic probe 20 is driven by vibratory movements at ultrasonic frequency in a manner well known in the ultrasonic welding technique. The ultrasonic probe 20 is then removed by upward movement.

In the embodiment shown in FIG. 8, an adjustable length of ribbon 1 is pulled by means of a transverse finger 21 with longitudinal displacement, the transverse finger 21 being initially in an intermediate position between the first loop with two slots 2 and the second loop 3, in a horizontal plane passing substantially through that of the second loop 3. In its longitudinal movement downstream, the transverse finger 21 passes over the first loop at two slots 2, so that an intermediate portion of ribbon 1 passes around the transverse finger 21 and is stretched downstream as shown in FIG. 8. As a result, the transverse finger 21 pivots downstream the portion of tape attached around the crossmember 6 of the first loop with two slots 2, and thus releases the upstream slot from the first loop with two slots 2 to allow the subsequent introduction of another portion of tape 1 into said upstream slot. The extreme position of the transverse finger 21 downstream is adjustable, so as to adjust the length of main tape 1 which will be used for the production of the bra strap. When the transverse finger 21 moves, the ribbon 1 is slightly braked by the reserve 10 of ribbon.

In FIG. 9, the first blank holder 22 is brought into abutment on the ribbon 1 in order to press it down and hold it against the second loop 3 downstream from the slot 23 of the second loop 3. This prevents the slipping of the ribbon 1 over the second loop 3 during subsequent operations. The ribbon 1 is cut by means of the ultrasonic probe 20 which has previously been displaced longitudinally upstream by the desired distance, the ultrasonic probe 20 then applying the ribbon 1 from top to bottom against a cutting anvil 24.

In FIG. 10, while maintaining the first blank holder 22 pressing on the ribbon 1, the second end 26 of ribbon 1 is introduced, by a threading finger of second loop 25, into the second loop 3 held horizontally in the second loop support, this operation being able to begin immediately after the start of the cutting operation shown in FIG. 9.

In the embodiment shown in Figure 11, the second loop 3 is moved longitudinally downstream, while longitudinally moving the transverse finger 21 downstream, to bring the second loop 3 in a downstream position relative to the first loop with two slots 2, and to bring the second end 26 of the main ribbon 1 in the vicinity of the first loop with two slots 2, the ribbon being placed on said first loop with two slots and the second end 26 of the ribbon 1 projecting in upstream of said first loop with two slots according to a predetermined length. The displacement of the second loop 3 and of the ribbon 1 is chosen so that the portion of ribbon 1 near its free end comes in front of the upstream slot of first loop with two slots 2. A relative movement of rotation of transverse axis has thus been carried out, around the crosspiece 6 of first loop with two slots 2, between said first loop with two slots 2 and the assembly formed by the ribbon 1 and the second loop 3.

In FIG. 12, a retaining finger, for example the first threading finger 14, is brought into abutment on the strip 1 to press it against the second slot 15 of the first loop with two slots 2, and a third finger is pressed threading, for example the first retaining finger 13, into the first slot 17 to introduce the second end 26 of tape into said first slot 17.

In FIG. 13, the second end 26 of tape is pushed back, by means of a fold-back means 27 with longitudinal displacement, on the other side of said first loop with two slots 2 in the direction of the second slot 15.

In FIG. 14, the folded end 26 is introduced into the second slot 15 by inserting a fourth threading finger 28 into said second slot, and while producing or allowing the displacement of the transverse finger 21 in the direction producing a relaxation of the tape 1 or, according to this embodiment, upstream in the direction of the first support of the first loop 2, at an appropriate distance. During insertion of the threading finger 28, the first threading finger 14 is withdrawn upwards.

Figures 15 to 17 illustrate the cutting to length of the main bra strap strap, by sliding in the loops 2 and 3. In Figure 15, there is shown, in top view, the assembly formed by the first loop with two slots 2, the second loop 3 and the main ribbon 1 in the position obtained after the step in FIG. 14. From this position, the first loop with two slots 2 and the second loop 3 are transferred respectively to a mobile support 29 of the first loop with two slots and on a mobile support 30 of the second loop. The mobile supports 29 and 30 are displaceable by transverse translation, as shown by the arrows 31 and 32.

In addition, the movable support 29 of the first loop with two slots 2 can be oriented by pivoting about a transverse axis of rotation, allowing the first loop with two slots to be turned over 180 °. In the initial position, shown in the Figure 15, the first loop with two slots 2 is positioned in such a way that the ribbon 1 leaves the slots through the upper face of the loop. After turning over, in the direction shown by arrow 33, the first loop with two slots 2 is such that the strip comes out from its underside, as shown in FIG. 16 on a larger scale.

According to a particular embodiment, the movable support 30 of the second loop 3 is also orientable by rotation along a transverse axis of rotation, ensuring the simultaneous reversal of the second loop 3. This reversal is however not necessary when it is desired simply ensure the length of the strap, without adaptation of an auxiliary tape.

After turning over, in the position of FIG. 16, the second end 26 of ribbon is hanging below the first loop with two slots 2, and is thus released and accessible. The ribbon 1 forms, between the two loops 2 and 3, an upper sheet relatively taut between the two loops, and a lower sheet which hangs relatively loosely below the loops. In the figure, this position of the lower ply has been represented by the dashed line designated by the reference 110. This lower ply constitutes an annoying obstacle for the subsequent stretching of the end 26 of the ribbon 1. To avoid this drawback, we move this lower ply 110 by a transverse finger 112, initially positioned in the vicinity of the first loop with two slots 2 as shown in phantom in Figure 16, the finger 112 being moved laterally by a jack 113 bringing it to the position shown in line full in the figure, position in which it supports the lower ply 111 of the ribbon 1.

When the lower ply of the ribbon 1 has taken the position 111, spaced from the end 26 of the ribbon, a movable roller 341 is displaced in the direction of a motor roller with a fixed rotary axis 340 to pinch the end 26 of the ribbon 1 between said rollers 340 and 341.

The second end 26 of the ribbon is pulled by rotation of the rollers 340 and 341 together constituting a traction means 34, to bring the ribbon to length, while retaining the second loop 3 away from the first loop with two slots 2.

FIG. 17 schematically represents the device at the end of stretching, when the ribbon is at the desired length. The movable roller 341 can then be brought back into the retracted position by the jack 342, and the finger 112 subsequently returns to the waiting position pushed back by the jack 113.

When it is not desired to assemble an auxiliary ribbon, the operation is then completed and the assembly formed by the ribbon and the two loops can be ejected. On the other hand, when it is desired to assemble an auxiliary ribbon, the operations continue as described below.

In FIG. 18, an additional element, called TAB, is brought onto the second loop 3, and comprising an auxiliary ribbon 35 unwinding from a reserve of auxiliary ribbon 36. It is caught, by means of a second movable clamp 37 , the first end 38 of the auxiliary tape 35, and said second movable clamp 37 is displaced longitudinally to pass the auxiliary tape 35 over the second loop 3.

In FIG. 19, a second blank holder 39 is lowered from bottom to top and brought to bear on the auxiliary tape 35 to press it down and hold it against the second loop 3 between the slot of said second loop 3 and the reserve of tape auxiliary 36. The end 38 of the auxiliary ribbon 35 is then introduced into the second loop slot 3 by threading an auxiliary threading finger 40 up and down in said second loop slot.

In FIG. 20, the end 38 of the auxiliary tape is folded back under the second loop 3 in the direction of the reserve 36 by longitudinal displacement of a folding member 41.

In FIG. 21, said end 38 of auxiliary tape 35 is welded against the inlet portion of auxiliary tape 35, between an auxiliary anvil 42 and an auxiliary ultrasonic probe 43.

In FIG. 22, the auxiliary ribbon is cut according to a determined length, for example by a cutter 44. The complete strap is then produced, and can be ejected from the device.

In one embodiment, the folding member 41 is constituted by the auxiliary anvil 42, which is, for this, made movable longitudinally between a withdrawal position shown on the left in FIG. 20 and an operating position shown on the right in Figure 21.

For the implementation of the method illustrated in FIGS. 3 to 22, the machine according to the present invention generally comprises two sub-assemblies: the first sub-assembly performs the steps of FIGS. 3 to 14, for assembling the main ribbon 1 on the loops 2 and 3; the second sub-assembly performs the cutting to length, according to the steps of FIGS. 15 to 17, and on the other hand the assembly of the auxiliary tape 35 according to the steps of FIGS. 18 to 22.

FIG. 23 illustrates the main functional members of the first sub-assembly of the machine according to the invention.

The machine comprises a frame 50 on which the functional members are mounted, and in particular a welding assembly 51, a second loop threading assembly 52, an upper first loop threading assembly 53, a lower threading assembly of first loop 54, a first loop support assembly 55, a second loop support assembly 56.

The welding assembly 51, the second loop threading assembly 52 and the upper first loop threading assembly 53 are all three mounted on a carriage 57 sliding on longitudinal guides 58 of the frame 50. A jack 59 controls the movement and the position of the carriage 57 along the longitudinal guides 58.

The lower first loop threading assembly 54 and the first loop support assembly 55 are fixed in longitudinal position on the frame. The second loop support assembly 56 is mounted on lower longitudinal guides 60 of the frame 50, and its position is controlled by the jack 620. The transverse finger 21 with longitudinal displacement, which ensures the stretching and the cutting to length of the ribbon , is integral with a carriage 630 slidably mounted on longitudinal guides of the frame 50 and controlled by a screw jack biased by the motor 61. This arrangement allows quick multi-position adjustment of the transverse finger 21.

In the embodiment shown in FIG. 23, the transverse stretching finger 21 is mounted at the end of a rod 210 which slides in a longitudinal bore of the carriage 630. The sliding of the rod 210 is limited by two stops, and the rod is biased upstream by a helical compression spring 211. This arrangement has a dual function:
- when you want to make a short strap, the second loop support 56 is close to the first loop support 55 in its initial position, and pushes back the transverse stretching finger 21 to against the thrust exerted by the spring 211, the finger 21 remaining in abutment against the support of the first loop 55 as long as it is not stressed by its jack and its motor 61;
- During the longitudinal translational movement of the support of the second loop 36 and of the transverse finger 21 of stretching, this arrangement allows different speeds and displacement races of the two elements controlled respectively by the motor 61 and by the jack 620.

There is shown, in the figure, a first loop with two slots 2, in position on its first loop support assembly 55, and a second loop 3 in position on its second loop support assembly 56. It is noted that the first loop 2 occupies a position slightly lower than the second loop 3. The first loop support assembly 55 also carries the welding anvil 19. The first folding means 16 is a transverse finger, integral with a carriage 63 with longitudinal sliding controlled by a bell cam 720 shown in FIG. 25. The transverse finger 16 is arranged below and near the first loop 2.

The cutting anvil 24, fixedly mounted on the frame 50, occupies a position upstream of the two loop supports 56 and 55.

At the outlet from the main ribbon reserve 10, the main ribbon 1 passes through guide means schematically represented 64, and through a non-return device 65.

In an advantageous embodiment illustrated in FIG. 32, the non-return device 65 is associated with means making it possible to pull and tension the ribbon 1 towards the rear before its welding around the central crosspiece 6 of the first loop to two slots 2. In this embodiment, the non-return device 65 clamps the ribbon 1 against a base plate 650, upstream of the support for the first loop with two slots 2. A jack 651 controls the descent of a clamp input blank 652, disposed upstream of the non-return device 65, the blank holder 652 pinching the ribbon 1 against the base plate 650, thereby locking the ribbon 1. The blank holder 652 is slidably mounted on the output rod 653 of the cylinder 651, and is pushed down against a stop 654 at the end of the rod by a spring 655. In the locked position, the blank holder 652 thus remains in elastic support against the strip 1. Simultaneously, a fork 656, integral with the rod 653, actuates a vier 657 causing the anti-tilt device to tip over return 65 which then releases the ribbon 1. The rod 653 continues its descent under the impulse of the cylinder 651, passing through the blank holder 652, and the stop 654 pushes a portion of ribbon 1 downwards into a cavity 658 of the base plate 650. The thrust of the intermediate part of the ribbon 1 by the stop 654, while the upstream part of the ribbon is blocked by the blank holder 652, produces a traction of the region of the first end 8 of the ribbon 1 towards upstream, the region of the first end of the ribbon 1 then sliding around the central crosspiece 6 of the first loop with two slots 2, the first end 8 of ribbon tending to approach the first loop with two slots 2. This operation significantly improves the quality of the first end weld 8 of the tape 1.

Again considering FIG. 23, the stretching clamp 12 is integral with a carriage 120 slidably mounted on longitudinal guides of the frame 50, and controlled by the jack 62 between a waiting position, shown in the figure, in which the clamp 12 is in the vicinity of the non-return device 65, and a stretching position in which the clamp 12 is downstream of the first strip support assembly 55.

The carriage 57 can move along the longitudinal guides 58 between a first position, shown in the figure, in which the ultrasonic probe 20, carried by the welding assembly 51, is opposite the cutting anvil 24, and a second position, not shown, in which the ultrasonic probe 20 faces the welding anvil 19. The ultrasonic probe 20 can be moved vertically on the welding assembly 51, between a first withdrawal position shown in the figure 23 and an operating position in which the ultrasonic probe 20 is in abutment against the corresponding anvil or against the strip placed on said anvil.

The second loop threading assembly 52 comprises on the one hand the first blank holder 22, actuated vertically by a blank holder cylinder 66 and on the other hand the second loop threading finger 25, actuated itself even vertically by the jack 67.

The upper assembly for threading the first loop 53 comprises the first threading finger 14 and the holding finger 13 or third threading finger, each driven by a vertical translational movement controlled by cams which will be described below. .

The lower assembly for threading the first loop 54 comprises the second threading finger 18 and the fourth threading finger 28, each driven by a vertical translation movement controlled by cams.

The functional members represented in FIG. 23 are controlled by the jacks and the cams to produce the movements described above in relation to FIGS. 3 to 14. The movements of the jacks can be obtained by any means within the reach of the skilled person. . We will describe below some details of the realization of the introduction finger drives by means of the cams.

In the embodiment shown in FIGS. 24 and 25, the drive in vertical translation of the threading fingers is ensured by cams carried by an upper drive shaft 68 and by a lower drive shaft 69. Both drive shafts 68 and 69 are parallel to each other and arranged in a longitudinal direction, journalling in bearings integral with the frame 50. The upper shaft 68 carries cams 70 on which come levers 71 of actuation of the threading fingers 13 and 14. The lower shaft 69 carries cams 72 on which come levers 73 for actuating the threading fingers 18 and 28 below, and carries the bell cam 720 for actuating the carriage 63 secured to the transverse finger 16. The upper shaft 68 and the lower shaft 69 are made integral in rotation with one another by a chain 74 mounted on two toothed wheels respectively secured to one and the other d es trees. The lower shaft 69 is driven in rotation by a drive assembly comprising an electric motor 75, a reduction gear 76 and a clutch-brake cell 77. The clutch-brake cell 77 allows the permanent rotation of the engine 75 and the rapid control of drive and stop of the shafts 68 and 69 during a fraction of the operating cycle, fraction corresponding for example to the longitudinal displacement of the second loop support 56 during the process phases shown in FIG. 11. This arrangement makes it possible to effectively control the threading fingers by 360 ° cams.

Note also in FIG. 24, a loop reserve 78 schematically represented, connected to the first loop support assembly 55 by loop supply guides 79. The loops can be stored, brought and selected by any known means , such as vibrant woods.

FIG. 26 schematically illustrates the two main sub-assemblies of the machine according to the invention, namely the sub-assembly 80 for assembling the main ribbon 1 on the loops 2 and 3 as described in FIG. 23 , and a sub-assembly 81 for stretching the main ribbon and assembling the auxiliary ribbon. At the end of assembly of the main ribbon 1 on the loops 2 and 3, the loops 2 and 3 are maintained in the first sub-assembly 80. The transfer of the loops 2 and 3 and of the main ribbon 1 in the second sub-assembly 81 is carried out by mobile supports, respectively a mobile support of the first loop 29 and a mobile support of the second loop 30. The mobile supports are driven in transverse translation by a jack 84, between a first position, shown in FIG. 26, in which they hold loops 2 and 3 in position in the second sub-assembly 81, and a second position, not shown in the figure, in which they are in the vicinity of the supports of first loop 55 and second loop 56 of the first sub- assembly 80, for receiving the loops which are ejected by ejection means not shown at the end of the assembly cycle of the main ribbon on the loops. The mobile supports 29 and 30 are each orientable by pivoting around a respective transverse axis of rotation, allowing the reversal of one and the other of the loops 2 and 3.

In Figure 27, for the sake of clarity, the mobile supports 29 and 30 have not been shown, only the first loop 2 and second loop 3 have been shown.

As shown in the figure, the auxiliary clamp 37 is slidably mounted on longitudinal guides 85 of the frame 50 and driven in longitudinal translation by a jack 86. An auxiliary carriage 87, also mounted on longitudinal guides 88 of the frame, is driven in translation by a jack 89. The carriage 87 carries on the one hand an auxiliary welding assembly 90 comprising in particular the auxiliary ultrasonic probe 43, and carries the auxiliary threading assembly 91 comprising the auxiliary threading finger 38, the clamp auxiliary blank 39, and their respective vertical actuating cylinders 92 and 95.

The auxiliary welding anvil 42 is slidably mounted on longitudinal guides 93 and driven in translation by a jack 94. The second sub-assembly 81 can thus, by the appropriate movements required, fulfill the functions described in relation to FIGS. 18 to 22, for assembling an auxiliary ribbon on the assembly formed by the main ribbon 1 and the loops 2 and 3.

The main ribbon stretching or lengthening assembly is generally designated in FIG. 27 under the reference 34. This assembly allows the functions described in relation to FIGS. 15 to 17. The assembly 34 comprises the motor roller with fixed rotary axis 340, driven by a schematically represented motor, disposed near the support of the first loop with two slots 2, and a second movable roller 341, disposed at the end of a lever actuated by the jack 342. Also shown is the transverse finger 112 and its actuating cylinder 113.

FIG. 28 illustrates the respective shapes of the first ultrasonic probe 20, the welding anvil 19 and the cutting anvil 24. This figure shows the ultrasonic probe 20 comprising a head provided with a groove 200 transverse center with flat bottom separating two flat portions 201 and 202 coplanar. The welding anvil 19 is a horizontal plate with generally planar support surface 190, preferably provided with reliefs giving it a grainy surface state. The cutting anvil 24 comprises a sharp transverse edge 240 shaped to engage in the groove 200 of the ultrasonic probe 20 and come to bear by its edge against the bottom of the groove 200.

There is shown in FIGS. 29 to 31 the detail of a particular embodiment of the means allowing the cutting and the insertion of the ribbon into the stretching clamp 12. In this embodiment, the cutting anvil 24 is arranged slightly below the horizontal plane along which the ribbon slides. At the time of cutting, shown in FIG. 29, the ribbon is folded due to the offset between the general plane of the ribbon and the position of the cutting anvil 24. It will be understood that, in order for the clamp 12 to correctly take the ribbon, straighten the end of the ribbon. This straightening is carried out by means of a guide tunnel 100, mounted with longitudinal sliding, and maintaining a portion of ribbon in the general plane of sliding of the ribbon. In the cutting position, shown in FIG. 29, the guide tunnel is pushed upstream by the jack 620 for supporting the second loop 56, against the thrust exerted by a spring 101. After cutting, the ultrasonic probe 20 is retracted upwards, and the guide tunnel 100 is moved downstream under the action of the thrust of the spring 101 or any equivalent means. During this movement, the guide tunnel 100 straightens the end of the ribbon. In FIG. 31, when the stretching clamp 12 takes hold of the ribbon, it pushes the guide tunnel 100 upstream against the thrust of the spring 101, the clamp then being in the open position. After closing the clamp 12, the ribbon is correctly pinched and can be stretched with great reliability. It is understood that the ribbon once cut is straightened by the guide tunnel 100, and the clamp can always grasp said end of straightened ribbon without the latter being able to fold back on itself.

A similar device can also be used in the second subassembly of the machine according to the invention, for cutting and gripping the auxiliary tape.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below.

Claims (20)

1 - Method for producing a garment strap such as a bra strap from a reserve of ribbon (1) with longitudinal unwinding, from a reserve of first loops with two slots (2) and d '' a reserve of second loops (3), characterized in that it comprises the succession of the following stages: a / a first loop with two slots (2) is introduced into a horizontal fixed support of the first loop by arranging the slots transversely with respect to the direction of longitudinal unwinding (11) of the ribbon, and a second loop (3) is introduced into a horizontal support of second suitable loop arranged upstream of the support of first loop with two slots, b / we catch, by means of a mobile clamp (12), the first end (8) of the reserve tape, and said movable clip is moved longitudinally by a fixed distance (L) determined to pass the tape (1 ) above the first loop with two slots (2) and bring its end beyond said first loop with two slots according to a predefined length (D), c / a holding finger (13) is brought into abutment from top to bottom on the strip (1) to pinch it against the first slot (17) of the first loop with two slots (2), d / we loosen the clamp (12) and we insert a first threading finger (14) from top to bottom in the second slot (15) of the first loop with two slots (2) to introduce the first end (8) of ribbon in said second slot, e / we fold this first end (8) of ribbon under the first loop with two slots (2), we introduce the folded end into the first slot (17) by inserting a second threading finger (18) from bottom to high in said first slot (17), f / the first end of the tape (1) coming out of the first slot is welded to the portion of the input tape between a soldering anvil (19) and an ultrasonic probe (20) arranged in the vicinity and upstream of the first loop with two slots, g / an adjustable length of ribbon is pulled by means of a movable transverse finger (21) around which an intermediate portion of ribbon passes, the first end of the ribbon being retained by the first loop with two slots, the reserve ribbon being braked by a device braking, h / the ribbon is cut, by means of the same ultrasonic probe (20) which has been displaced longitudinally upstream by the desired distance, and the second is introduced by a second loop threading finger (25) end (26) of ribbon, according to a predefined length, in the second loop (3) held horizontally in the second loop support, i / between the first loop with two slots (2) and the assembly formed by the ribbon (1) and the second loop (3), a relative movement of rotation of transverse axis is carried out around the central crosspiece (6 ) of the first loop with two slots (2), to release the first slot (17) of the first loop with two slots (2), and the second end (26) of tape is brought against the face of the first loop with two slots by which exits the ribbon, in the vicinity of the first slot (17), j / a holding finger (14) is brought to bear on the strip to press it against the second slot (15) of the first loop with two slots (2), and a third threading finger (13) is pressed into the first slot (17) for introducing the second end (26) of ribbon into said first slot, said second end (26) of ribbon is folded over the other side of said first loop (2) in the direction of the second slot (15 ), the folded end (26) is introduced into the second slot (15) by inserting a fourth threading finger (28) into said second slot, k / the assembly thus produced is ejected. 2 - Method according to claim 1, characterized in that one produces or allows the displacement of the transverse finger (21) in the direction producing a relaxation of the ribbon (1), by an appropriate distance, during the insertion of the fourth finger threading (28) into the second slot (15). 3 - Method according to one of claims 1 or 2, characterized in that, between steps e / and f /, the ribbon (1) is pulled upstream to make it slide around the central crosspiece (6) first loop with two slots (2) and bring its first end (8) in the immediate vicinity of the first loop with two slots (2). 4 - Process according to any one of claims 1 to 3, characterized in that, during step h /, a first blank holder (22) is brought into abutment on the ribbon to press it down and hold it against the second loop (3) downstream of the second loop slot. 5 - Method according to any one of claims 1 to 4, characterized in that, between steps j / and k /, it comprises the following intermediate steps: l / the loops (2, 3) are transferred laterally to two respective mobile supports (29, 30), m / the movable support (29) of the first loop with two slots is turned 180 ° to release the second end (26) of tape, n / the second end (26) of ribbon is pulled with a pulling means to bring the strap to length, while retaining the second loop (3) away from the first loop with two slots (2). 6 - Method according to any one of claims 1 to 5, characterized in that:
- during step g /, the transverse finger (21) is moved longitudinally over the first loop with two slots (2) between a first upstream position and a second downstream position,
- Step i / is carried out by longitudinal displacement of the second loop (3) over the first loop with two slots (2) to a position located downstream of the first loop with two slots (2). 7 - Method according to claim 6, characterized in that, prior to step n /, the lower sheet (110) of ribbon is moved away from the second end (26) of ribbon. 8 - Method according to one of claims 6 or 7, characterized in that: o / simultaneously with step n /, the mobile support (30) of the second loop is turned 180 ° to bring the second loop (3) to the threading position, p / an additional element called TAB is brought onto the second loop (3), and comprising an auxiliary ribbon (35), by placing the end of the auxiliary ribbon on said second loop, q / the end of the auxiliary ribbon is introduced into the second loop slot by threading an auxiliary threading finger (40) from top to bottom, said end is folded under the second loop by longitudinal movement of a folding member ( 41), said end (38) of auxiliary ribbon (35) is welded against the auxiliary ribbon inlet portion between an auxiliary anvil and an auxiliary ultrasonic probe, the auxiliary ribbon is cut according to a determined length. 9 - Method according to claim 8, characterized in that the folding member (41) is constituted by the auxiliary anvil, which is movable longitudinally to fold the auxiliary ribbon. 10 - Method according to one of claims 8 or 9, characterized in that, during step q /, during the introduction of the auxiliary tape (35) in the second loop slot, it brings a blank holder (39 ) by pressing on the auxiliary ribbon to press it and hold it against the second loop. 11 - Machine implementing a method according to any one of claims 1 to 10, for the production of a garment strap such as a bra strap, comprising a frame (50), a reserve of tape ( 10), a reserve of first loops with two slots, a reserve of second loops, a first horizontal support (55) for maintaining a first loop with two slots, a first horizontal support (56) for maintaining a second loop, means for bringing loops from the reserves of loops into the loop supports, a movable clamp (12) actuated by a drive means for catching the end of the ribbon at the outlet of the reserve of ribbon and the bringing along a longitudinal path beyond the first support (55) of the first loop with two slots, two upper fingers for threading (13, 14) of tape and two lower fingers for threading (18, 28) of tape, vertical displacement, arranged opposite the two slots of the first loop (2) with two slots on either side of said loop, means for driving the threading fingers in vertical translational movements generally perpendicular to the first loop, fingers (16) for folding fold the end of the ribbon under the first loop with two slots between the second and the first slot, means (19, 20) for welding the ribbon around the central branch of the first loop with two slots and means (20, 24 ) to cut the ribbon,
characterized in that:
the first support (55) of the first loop with two slots is fixed in the longitudinal position on the frame (50),
the means for welding the tape comprise an ultrasonic probe (20) movable in longitudinal displacement parallel to the direction (11) of displacement of the tape between a welding position in which the ultrasonic probe (20) is disposed in the vicinity of the first support ( 55) of the first loop with two slots opposite a welding anvil (19) and a cutting position in which the ultrasonic probe (20) is arranged in the vicinity and upstream of the first second loop support (56) opposite a cutting anvil (24), the same ultrasonic probe (20) successively ensuring the functions of welding member and cutting member,
- a transverse horizontal finger (21) with longitudinal displacement is driven by longitudinal drive means between a first position in which the finger (21) occupies an intermediate zone between the two first supports (55, 56) of loops and a second position in which the finger (21) is downstream of the first support (55) of the first loop with two slots, the second position of the transverse finger (21) being adjustable by longitudinal displacement as a function of the length of the strap to be produced. 12 - Machine according to claim 11, characterized in that the upper threading fingers (13, 14) of tape and the ultrasonic probe (20) are mounted on a carriage (57) sliding on guides (58) longitudinal of the frame , to ensure the necessary longitudinal movement of the ultrasonic probe (20) between the welding position and the cutting position. 13 - Machine according to claim 12, characterized in that it further comprises a threading second loop finger (25) and a first blank press (22) mounted on said carriage (57), to press the tape against the second loop (3) and insert it into the second loop slot. 14 - Machine according to any one of claims 11 to 13, characterized in that:
- It further comprises a mobile support for the first loop (29) and a mobile support for the second loop (30), which can be moved transversely and are intended to receive the loops ejected respectively from the first support for the first loop (55) and the first support for second loop (56),
the mobile support (29) of the first loop with two slots is rotatably mounted along a transverse axis allowing the turning of said first loop with two slots according to 180 °,
- traction means (34) make it possible to grip the hanging end (26) of the ribbon of the first loop with two slots and to pull it to put the strap at the desired length while the second loop is retained in its movable support (30) of the second loop away from the first loop with two slots. 15 - Machine according to claim 14, characterized in that it further comprises a reserve of auxiliary tape (36), an auxiliary tape threading finger (40) opposite the movable support (30) of the second loop, a folding member (41) for folding the end of the auxiliary tape at the movable second loop support, an ultrasonic welding device (42, 43) disposed in the vicinity of the movable second loop support, means making it possible to cut the auxiliary tape at the desired length away from the movable support of the second loop, so as to have in the second loop (3) an auxiliary tape (35). 16 - Machine according to claim 15, characterized in that the ultrasonic welding means disposed in the vicinity of the movable support (30) of the second loop comprises an auxiliary anvil (42) and an auxiliary ultrasonic probe (43), the auxiliary anvil (42) being movable longitudinally under the movable support of the second loop to alternately fulfill the function of anvil anvil for welding and the function of folding device for the flap of the end of the auxiliary tape opposite the movable support of second loop. 17 - Machine according to any one of claims 14 to 16, characterized in that the movable support of the second loop (30) is rotatably mounted along a transverse axis allowing the reversal of said second loop according to 180 °. 18 - Machine according to any one of claims 11 to 17, characterized in that the cutting anvil (24) is associated with a horizontal sliding guide tunnel (100), mounted with longitudinal sliding between a cutting position in which the tunnel is spread to allow access to the cutting anvil (24) for cutting the ribbon, and a holding position in which the tunnel covers the cutting anvil (24) and straightens the ribbon. 19 - Machine according to any one of claims 11 to 18, characterized in that:
the ultrasonic probe (20) comprises a head provided with a transverse central groove with a flat bottom separating two planar coplanar portions,
- the welding anvil (19) is generally a horizontal plate plane,
- The cutting anvil (24) comprises a sharp transverse edge shaped to engage in the groove of the ultrasonic probe (20) and come to bear by its edge against the bottom of the groove. 20 - Machine according to any one of claims 11 to 19, characterized in that the transverse horizontal stretching finger (21) is mounted at the end of a longitudinal rod (210) sliding in the carriage (630) drive finger, the rod being associated with a spring (211) pushing it upstream, so that the horizontal stretching finger (21) can be pushed downstream by the second loop support (56).

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